From bb45012c3918a5cc17f36e72026112a34a5734c9 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Sun, 22 Apr 2018 11:48:38 +0200
Subject: [PATCH] mes: Add isatty?.

* src/posix.c (isatty_p): New function.
---
 lib/libc.c  | 2 +-
 src/posix.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/libc.c b/lib/libc.c
index 97565c31..2819468c 100644
--- a/lib/libc.c
+++ b/lib/libc.c
@@ -424,7 +424,7 @@ sprintf (char *str, char const* format, ...)
 int
 isatty (int fd)
 {
-  return ioctl (fd, TCGETS, 0) == -14; // MAGIC
+  return ioctl (fd, TCGETS, 0) & 0xf0;
 }
 
 #endif //!POSIX
diff --git a/src/posix.c b/src/posix.c
index 2e6b3a8c..f0a020d9 100644
--- a/src/posix.c
+++ b/src/posix.c
@@ -199,3 +199,9 @@ force_output (SCM p) ///((arity . n))
 {
   return cell_unspecified;
 }
+
+SCM
+isatty_p (SCM port)
+{
+  return isatty (VALUE (port)) ? cell_t : cell_f;
+}